In heat exchangers employing a multiplicity of conduits having a polygonal or oval configuration in cross-section, the fabrication of a fluidtight tubesheet in which the end portions of such conduits are supported is difficult and expensive. More specifically, the construction of non-circular openings in a plate type tubesheet and the subsequent securing of non-circular conduits, such as disclosed in the patent to Kritzer U.S. Pat. No. 3,229,722 dated Jan. 18, 1966, in those openings requires complex and expensive machining and bonding operations. In the built-up tube and tubesheet assembly according to this invention these disadvantages and shortcomings of prior apparatuses are overcome.
Accordingly, it is an object of this invention to provide a built-up tube and tubesheet assembly for supporting conduits of non-circular cross-section which assembly is relatively easy and inexpensive to fabricate. It is a further object to provide a built-up tube and tubesheet assembly having conduits of non-circular cross-section which assembly has structural integrity and optimum sealing of the joints between the tube elements and tubesheet. It is another object of the present invention to provide a method of fabricating a built-up tube and tubesheet assembly for supporting conduits of non-circular cross-section, which method is relatively simple and low in cost.